add implementation of is_in_tree

risc0-selective-privacy-poc/core/src/account.rs

@@ -47,13 +47,23 @@ pub fn hash(bytes: &[u32]) -> [u32; 8] {
     Impl::hash_words(bytes).as_words().try_into().unwrap()
 }
 
-/// Dummy implementation
-pub fn is_in_tree(
-    _commitment: Commitment,
-    _auth_path: &AuthenticationPath,
-    _tree_root: [u32; 8],
-) -> bool {
-    true
+pub fn is_in_tree(commitment: Commitment, path: &AuthenticationPath, root: [u32; 8]) -> bool {
+    const HASH_ONE: [u32; 8] = [
+        789771595, 3310634292, 3140410939, 3820475020, 3591004369, 2777006897, 1021496535,
+        2588247415,
+    ];
+
+    let mut hash = HASH_ONE;
+    let mut current_index = commitment;
+    for path_value in path.iter() {
+        if current_index & 1 == 0 {
+            hash = hash_two(&hash, path_value);
+        } else {
+            hash = hash_two(path_value, &hash);
+        }
+        current_index >>= 1;
+    }
+    root == hash
 }
 
 /// Returns Hash(Commitment || private_key)
@@ -64,7 +74,14 @@ pub fn compute_nullifier(commitment: &Commitment, private_key: &Key) -> Nullifie
     hash(&bytes_to_hash)
 }
 
-pub fn bytes_to_words(bytes: [u8; 32]) -> [u32; 8] {
+fn hash_two(left: &[u32; 8], right: &[u32; 8]) -> [u32; 8] {
+    let mut bytes_to_hash = [0; 16];
+    bytes_to_hash[..8].copy_from_slice(left);
+    bytes_to_hash[8..].copy_from_slice(right);
+    hash(&bytes_to_hash)
+}
+
+pub fn bytes_to_words(bytes: &[u8; 32]) -> [u32; 8] {
     let mut words = [0; 8];
     for (i, chunk) in bytes.chunks(4).enumerate() {
         words[i] = u32::from_le_bytes(chunk.try_into().unwrap());

risc0-selective-privacy-poc/src/private_execution.rs

@@ -3,7 +3,7 @@ use rand::{rngs::OsRng, Rng};
 use risc0_zkvm::{default_prover, ExecutorEnv, Receipt};
 use sparse_merkle_tree::SparseMerkleTree;
 use toy_example_core::{
-    account::{bytes_to_words, Account, Address, Commitment, Nonce, Nullifier},
+    account::{bytes_to_words, Account, Address, AuthenticationPath, Commitment, Nonce, Nullifier},
     input::InputVisibiility,
 };
 use transfer_methods::{TRANSFER_ELF, TRANSFER_ID};
@@ -31,9 +31,15 @@ fn run_private_execution_of_transfer_program() {
         account.balance = 150;
         account
     };
+
     let commitment_tree = SparseMerkleTree::new([sender.commitment()].into_iter().collect());
-    let root = bytes_to_words(commitment_tree.root());
-    let auth_path = commitment_tree.get_authentication_path_for_value(sender.commitment());
+    let root = bytes_to_words(&commitment_tree.root());
+    let auth_path: Vec<[u32; 8]> = commitment_tree
+        .get_authentication_path_for_value(sender.commitment())
+        .iter()
+        .map(bytes_to_words)
+        .collect();
+    let auth_path: AuthenticationPath = auth_path.try_into().unwrap();
 
     let balance_to_move: u128 = 3;
 
@@ -46,7 +52,7 @@ fn run_private_execution_of_transfer_program() {
     let (inner_receipt, inputs_outputs) = prove_inner(&sender, &receiver, balance_to_move);
 
     let visibilities = vec![
-        InputVisibiility::Private(Some((sender_private_key, [[0; 8]; 32]))),
+        InputVisibiility::Private(Some((sender_private_key, auth_path))),
         InputVisibiility::Private(None),
     ];